2. Foreword
FM Approvals are intended to verify that the products and services described will meet stated conditions of
performance, safety and quality useful to the ends of property conservation. The purpose of FM Approval
Standards is to present the criteria for FM Approval of various types of products and services, as guidance for
FM Approvals personnel, manufacturers, users and authorities having jurisdiction.
Products submitted for Approval shall demonstrate that they meet the intent of the Approval Standard, and that
quality control in manufacturing and/or applications shall ensure a consistently uniform and reliable product or
service. FM Approval Standards strive to be performance-oriented and to facilitate technological development.
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For examining equipment, materials and services, FM Approval Standards:
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a) must be useful to the ends of property conservation by preventing, limiting or not causing damage
under the conditions stated by the Approval listing; and
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b) must be readily identifiable.
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Continuance of Approval and Listing depends on compliance with the Approval agreement, satisfactory
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performance in the field, on successful re-examinations of equipment, materials, and services as appropriate, and
on periodic follow-up audits of the manufacturing facility or service/application.
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FM Global Technologies LLC reserves the right in its sole judgement to change or revise its standards, criteria,
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methods, or procedures.
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3. TABLE OF CONTENTS
INTRODUCTION .......................................................................................................................................................................... 1
REQUIREMENTS ........................................................................................................................................................................... 1
Durability ................................................................................................................................................................................... 1
Audibility ................................................................................................................................................................................... 1
Sensitivity .................................................................................................................................................................................. 1
Port Sizes ................................................................................................................................................................................... 2
Inlet and Outlet .......................................................................................................................................................................... 2
Moving Parts .............................................................................................................................................................................. 2
Water Motor Housing ................................................................................................................................................................ 2
Accessibility for Service ........................................................................................................................................................... 2
Protective Cover ........................................................................................................................................................................ 2
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Materials .................................................................................................................................................................................... 3
Markings .................................................................................................................................................................................... 3
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4. July 1970 1055
INTRODUCTION
A water motor gong is used to give a locally audible alarm signal when a fire protection sprinkler system
operates. Such a device should be highly reliable and durable.
FM Approval is based on examination and test of production samples, inspection of the manufacturing and/or
quality control facilities, and use experience. Particularly considered are functional suitability, adequacy of
design and workmanship, uniformity and dependability of production, effectiveness of quality control, and
assurance of service and of replacement parts.
Minimum physical requirements given below are guides. Mere conformity does not assure Approval since other
considerations may control. Nor is strict conformity necessary; devices having different characteristics may be
considered and Approved, if shown to be essentially equivalent or superior in performance.
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REQUIREMENTS
Durability a se
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The water motor gong shall be designed to operate reliably without excessive maintenance. It will be subjected
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to a 60-hour continuous endurance run with an average operating pressure of 50 psi at the inlet to the device.
No lubrication or adjustment will be made during this test. There shall be no evidence of any excessive wear at
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the completion of the test.
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Audibility
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The water motor gong shall produce an audible signal sufficient to alert a nearby plant employee during working
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hours or a guard or other person during idle hours. The sound should be loud enough and of such a pitch as to
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be clearly heard, above the average factory noise levels, at a distance of several hundred feet.
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It shall generate sound waves having a minimum sound-pressure level of 90 decibels (referred to a 0.0002
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microbar base) using the ‘‘C’’ weighting, when tested in a room having a background noise level within the
approximate range of 50 to 55 decibels and using 30 lb operating pressure at the inlet to the gong. Sound pressure
level measurements will be made at a point 10 ft in front of the gong with the protective cover in place.
Sensitivity
Operation shall commence at a maximum pressure of 5.0 psig measured at the inlet to the device, upstream of
the strainer, when the pressure is increased from zero.
FM APPROVALS 1
5. 1055 July 1970
Port Sizes
Operating ports such as nozzles shall have a diameter of not less than 1⁄8 in. and be protected by a suitable strainer
of corrosion-resistant material. The total area of all openings in the strainer screen shall be at least ten times the
port area.
The strainer, which shall be furnished by the gong manufacturer, may be located at the waterflow detecting
device.
Inlet and Outlet
The inlet opening shall be suitable for connection to 3⁄4 in. IPS supply piping.
The outlet opening shall be of ample size to facilitate the removal of waste water. A connecting pipe in the order
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of 1 to 11⁄2 in. IPS will be acceptable.
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Moving Parts
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Shafts and other moving parts shall be designed to prevent binding and protected against mechanical injury.
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Bearings shall be self lubricating or have means for lubrication. The lubricant must be suitable for use over the
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range of temperatures between -60°F and 110°F.
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Water Motor Housing
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The water motor housing shall be able to withstand a hydrostatic pressure of 200 psig for 5 minutes.
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Accessibility for Service
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Design must permit disassembly for inspection, lubrication, adjustment or repair without removal from the
supporting wall or structure.
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Suitable means shall be provided so that nozzle and strainer can be readily cleaned.
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Protective Cover
An outer shield or protective cover shall be provided to protect the gong from deteriorating effects of rain and
snow and to prevent nesting of birds, vermin, etc.
A combination gong-cover shall be able to withstand six (6) blows from a 101⁄2 lb. steel ball, swinging as a 101⁄2
ft. long pendulum, hung directly over the gong from a height of five (5) feet. Point of contact between ball and
gong-cover will be halfway between center of gong-cover and its periphery on a horizontal plane.
Following this test, the operating water motor gong shall still sound an audible alarm.
2 FM APPROVALS
6. July 1970 1055
Materials
All materials used shall be suitable for the intended application.
Markings
The shield shall carry the words ‘‘SPRINKLER ALARM’’ having a minimum letter height of 1 in. The lettering
may be cast on the shield or may be on a separate plate which shall be substantially fastened to the shield. Cast
letters shall be raised approximately 3⁄32 in.
The body of the device (motor housing) shall be marked with the manufacturer’s name or trade mark, and a
distinctive model or figure number.
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FM APPROVALS 3
